If you don't have any engine stumble @ WOT, or notice a decrease in fueling @WOT, you guys are probably okay. 1-2 psi's is below what I would want in my truck, but the decision is really up to you as I believe they will not warranty a new lift pump if you are seeing 11-12 psi's @ idle. Guess you could try, though, I've heard that a complaint of difficult starting may get some action in regards to a warranty replacement.
I would not add any type of fueling boxes or larger injectors with those readings, would probably drag you down to 0 psi's real quick. I would strongly consider either A). drilling out those banjo bolts or B) going with a new fuel line system that removes the banjo's entirely, that would surely help .
Just my opinion with my limited experience, so take it for what it's worth. Again, maybe a more experienced TDR member can jump in here for his/her viewpoint.
When my Carter was showing 0-1 psi's @ WOT, I swapped it out for the Mallory 4150 pump, which was then located back where a lift pump should be, adjacent to the fuel tank and below same. One thing we have found out is that lift pumps are happier pushing the fuel forward, rather than pulling it forward. Hope this helps.
Scott W.
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